Lasers are commonly used to generate light. One type of laser includes a wave guided gain media, a collimating optics (collimator), and a plane diffraction grating, retroreflacting light, which together define an external cavity for the laser. This type of laser is commonly referred to as having a Littrow configuration. In this configuration, light generated by the gain media is directed through the collimator at the diffraction grating, and the diffraction grating reflects the light back to the gain media through the collimator. With this design, the primary wavelength of the light generated by the laser is dependent upon the angle of incidence of the collimated light of the diffraction grating.
In certain designs, it is desirable that the laser is adapted to be selectively and continuously tuned across desired wavelength (or frequency) range. With a Littrow type laser, the output wavelength can be adjusted continuously by simultaneous adjustment of the grating angle with respect to the incident beam and a cavity length of the external cavity.
Some prior art laser designs have suggested that a unique pivot axis exists about which the diffraction grating can be pivoted to move the diffraction grating relative to the gain media to continuously adjust the wavelength of the output light. Unfortunately, none of the prior art laser designs have properly located the unique pivot axis. As a result thereof, these prior art lasers suffer from mode hops that lead to frequency jumps in the output light. Thus, the prior art lasers are not able to accurately provide a continuously tunable output light.